To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
In recent, as prevalence of smart phones accelerates, a variety of application services using the smart phone is activated. It is expected that such an aspect will accelerate more. Hence, various techniques for effectively preventing data increase due to various application services in a cellular system are emerging. For example, as massive mobile contents are used, Device to Device (D2D) communication for efficiently distributing load of a base station using proximity of a mobile communication terminal is drawing attention. For example, the D2D is adopted as a study item of current 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) release 12 and standardized by Radio Access Network (RAN)1.
LTE standardizes the D2D communication for the sake of public safety. That is, the D2D communication is to fulfill reliable communication between devices when a base station is collapsed due to a natural disaster such as earthquake or tsunami. Also, when an urgent operation such as fire and terror suppression is conducted, the D2D communication in a region (e.g., a shadow area and a base station coverage hole) outside coverage of the base station needs to seamlessly perform the communication between devices without aid of the base station. Thus, ensuring link reliability is more important than increasing band efficiency or system throughput which was a requirement of an existing cellular communication.
The conventional cellular system supports control information of various types. However, the D2D communication under the standardization for the current LTE Rel-12 may not need all of such control information. For example, as the current D2D communication aims at groupcast/broadcast communication, rather than unicast communication mostly used in the cellular, 3GPP RAN1/RAN2 meeting already agreed not to perform any type of Layer1 (L1:PHY)/L2 (Media Access Control (MAC), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC)) feedbacks. On this assumption, research on which control information is required for the D2D groupcast/broadcast communication is demanded.
Also, an existing cellular Frequency Division Duplexing (FDD) system uses different frequency bands for uplink and downlink transmission/reception (e.g., f1 band for the downlink, f2 band for the uplink). Accordingly, the base station transmits over the f1 band and receives over the f2 band, and the device transmits over the f2 band and receives over the f1 band. Meanwhile, in an existing cellular Time Division Duplexing (TDD) system, the downlink and the uplink are conducted in the same frequency band but are time-divided and used. That is, the uplink and downlink transmissions are divided and conducted on a frequency or a time axis.
However, the D2D communication performs transmission/reception in the uplink. For example, provided that the D2D communication operates in the FDD system, a D2D transmitter transmits over the uplink f2 band and a D2D receiver receives over the uplink f2 band. Similarly, in the D2D communication operating in the TDD system, a D2D transmitter transmits using uplink subframes and a D2D receiver receives using uplink subframes. Since the D2D communication is performed through the uplink, it is possible to consider reusing Uplink Control Information (UCI) and Physical Uplink Control CHannel (PUCCH) which were used in the existing cellular system, as control information and a control channel for the D2D. However, the uplink in LTE employs Single Carrier (SC)-Frequency Division Multiple Access (FDMA) having better Peak-to-Average Power Ratio (PAPR) characteristic than Orthogonal FDMA (OFDMA), regardless of the FDD/TDD. When one device transmits over the PUCCH and a Physical Uplink Shared CHannel (PUSCH) at the same time, the single carrier characteristic cannot be retained and thus it is not advantageous to transmit D2D control information over the PUCCH. Hence, it is demanded to design a new control channel for the D2D.
Also, in the existing cellular system, the base station performs centralized resource allocation based on various feedback information from the device. However, since the D2D communication does not have the feedback information between devices, a method for performing distributed resource allocation is demanded. The distributed resource allocation can suffer from a resource collision due to the same resource allocation because it does not have a coordinator for arbitrating in the resource allocation. Thus, measures for addressing this are demanded.